KR101830742B1 - Interference management for mobile relay in full-duplex radio communication system - Google Patents

Interference management for mobile relay in full-duplex radio communication system Download PDF

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KR101830742B1
KR101830742B1 KR1020167010205A KR20167010205A KR101830742B1 KR 101830742 B1 KR101830742 B1 KR 101830742B1 KR 1020167010205 A KR1020167010205 A KR 1020167010205A KR 20167010205 A KR20167010205 A KR 20167010205A KR 101830742 B1 KR101830742 B1 KR 101830742B1
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station
signal
base station
time interval
information
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KR20160067870A (en
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김기태
김진민
노광석
최국헌
정재훈
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엘지전자 주식회사
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Priority to PCT/KR2014/003851 priority patent/WO2015060510A1/en
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/155Ground-based stations
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/155Ground-based stations
    • H04B7/15564Relay station antennae loop interference reduction
    • H04B7/15585Relay station antennae loop interference reduction by interference cancellation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/155Ground-based stations
    • H04B7/15507Relay station based processing for cell extension or control of coverage area
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/24Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2603Arrangements for wireless physical layer control
    • H04B7/2606Arrangements for base station coverage control, e.g. by using relays in tunnels
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00Arrangements affording multiple use of the transmission path
    • H04L5/14Two-way operation using the same type of signal, i.e. duplex
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W4/00Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/06Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W72/00Local resource management, e.g. wireless traffic scheduling or selection or allocation of wireless resources
    • H04W72/04Wireless resource allocation
    • H04W72/08Wireless resource allocation where an allocation plan is defined based on quality criteria
    • H04W72/082Wireless resource allocation where an allocation plan is defined based on quality criteria using the level of interference
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022Site diversity; Macro-diversity
    • H04B7/026Co-operative diversity, e.g. using fixed or mobile stations as relays
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413MIMO systems

Abstract

Disclosed herein are a method and apparatus for managing interference. In one example, the first station receives the first signal from the base station, and the second station obtains information about the particular processing scheme of the second station for processing to transmit the first signal to the third station. Thereafter, the second station receives the second signal from the base station while transmitting the first signal to the third station, and based on the knowledge of the first signal and the information about the particular processing scheme, And can manage the interference caused by the first signal transmission from the station.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an interference management of a mobile agent in an omni-directional wireless communication system.

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for controlling interference by a mobile mediator in a full-duplex wireless communication system.

As an example of a wireless communication system to which the present invention can be applied, a 3GPP LTE (Third Generation Partnership Project Long Term Evolution) communication system will be schematically described.

FIG. 1 is a diagram schematically illustrating an E-UMTS (Evolved Universal Mobile Telecommunications System) network structure as an example of a wireless communication system. E-UMTS is a system that evolved from existing UMTS, and is currently undergoing basic standardization work in 3GPP. E-UMTS is generally referred to as an LTE system. For details of the technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of "3rd Generation Partnership Project (Technical Specification Group Radio Access Network)" respectively.

Referring to FIG. 1, an E-UMTS is a terminal located at the end of a user equipment (UE), an eNode B (eNB), and an evolved UMTS terrestrial radio access network (E-UTRAN) And an access gateway (AG). The eNB may simultaneously transmit multiple data streams for broadcast services, multicast services, and / or unicast services.

One eNB may have more than one cell. Cell is set to one of the bandwidths of 1.25, 2.5, 5, 10, 15, 20Mhz and the like to provide a downlink (DL) or uplink (UL) transmission service to multiple UEs within a bandwidth. Different cells may be set up to provide different bandwidths. The eNB controls data transmission and / or reception for a plurality of UEs. For the downlink data, the eNB transmits downlink scheduling information to inform the corresponding UE of the time / frequency resource, coding, data size, and HARQ related information to be transmitted. Also, the eNB transmits uplink scheduling information to the corresponding UE for uplink data, and notifies the UE of time / frequency resources, coding, data size, and HARQ related information that the UE can use. An interface for transmitting user traffic or control traffic may be used between eNBs. The core network (CN) may be configured as a network node for user registration of the AG and the UE. The AG manages the mobility of the UE in a tracking area (TA) composed of a plurality of cells. One TA consists of several cells.

Wireless communication technology has advanced to LTE based on wideband code division multiple access (WCDMA), but the demand and expectations of users and service providers are increasing. Considering other wireless access technologies under development, new technology evolution is required to secure high competitiveness in the future. Reduced interference, reduced cost per bit, increased service availability, flexible use of frequency bands, simplified architecture, open interfaces, and adequate power consumption of terminals.

It is therefore an object of the present invention to provide a method and an apparatus for controlling a mobile repeater interference in a full-duplex wireless communication system capable of solving one or more problems due to limitations and disadvantages of the related art.

The advantages, objects and features according to the present invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art upon examination of the following description, It is possible. The problems to be solved by the present invention and other advantages may be realized and attained by a specific structure in the following description, the claims and the accompanying drawings.

Methods and apparatus for accomplishing these and other advantages in accordance with the purpose of the present invention will now be described and fully described.

To this end, in a mobile communication system, a first station receives a signal from a base station, the method comprising: receiving a first signal from the base station and transmitting the first signal to a third station Obtaining information about a particular processing scheme of the second station for processing and receiving the second signal from the base station while the second station is transmitting the first signal to the third station, And managing the interference caused by the first signal transmission from the second station based on the knowledge about the specific protocol and the information about the particular protocol scheme.

The specific processing scheme may include at least one of a modulation and coding scheme, a precoding scheme, and a resource allocation scheme.

The first signal may be a broadcast signal broadcast by the base station to a plurality of stations including the second station.

The information on the particular processing scheme may be obtained by receiving information on the particular processing scheme from the second station.

The information on the specific processing scheme can be obtained by estimating information on the specific processing scheme in the first station.

The information on the particular processing scheme may be obtained by receiving information on the particular processing scheme from the base station.

The first station may be a terminal directly served by the base station, the second station may be a repeater, and the third station may be another terminal serviced by the repeater.

According to another aspect of the present invention, there is provided a method of relaying a signal in a mobile communication system, the method comprising: receiving a signal to be transmitted from a base station to a second station; processing the received signal according to a particular method; Transmitting the processed signal to the second station while one or more of the third stations serviced by the base station are receiving another signal and transmitting information about the particular manner to one or more of the base station and the third station And a signal relaying method.

The information on the particular scheme may be used by the at least one of the base station and the third station to manage interference generated by transmitting the processed signal to the second station.

Wherein at least one of the base station and the third station is aware of the received signal and at least one of the base station and the third station manages the interference based on information about the particular scheme and knowledge of the received signal .

The mobile communication system can use an FDR (Full-Duplex Radio) communication method.

The first station may be a repeater, the second station may be a terminal serviced by the repeater, and the third station may be another terminal serviced by the base station.

According to another aspect of the present invention, there is provided a method of receiving a signal in a mobile communication system, the method comprising: transmitting a first signal to a first station, Wherein the first station receives the second signal from the third station while the first station is transmitting the first signal to the second station, A method of receiving a signal that manages interference caused by a station transmitting the first signal based on information about the specific processing method and knowledge about the first signal.

According to another aspect of the present invention, there is provided an apparatus operating as a first station in a mobile communication system for relaying a signal, comprising: a transceiver for receiving a signal from a base station; And a processor coupled to the transceiver for processing signals received by the transceiver based on a particular scheme for transmitting to a second station, wherein the processor is operable to receive one of the base stations and a third station serviced by the base station, Wherein the transceiver is configured to transmit the processed signal to the second station while the second transceiver is receiving another signal, and to control the one or more of the base station and the third station to transmit information about the specified method, Device.

In another aspect of the present invention, there is provided an apparatus operating as a first station for receiving a signal from a base station in a mobile communication system, the apparatus comprising: a first station for transmitting a first signal, A transceiver for receiving a second signal from the base station while the second station is transmitting the first signal to the third station; And a processor coupled to the transceiver for managing interference caused by the first signal transmitted from the second station based on knowledge of the first signal and information on the particular processing scheme, Lt; / RTI >

According to another aspect of the present invention there is provided an apparatus operating as a base station in a mobile communication system, the apparatus comprising: a transmitter for transmitting a first signal to a first station, A transceiver for receiving information on a method, the first station receiving a second signal from a third station while transmitting the first signal to the second station; And a base station apparatus connected to the transceiver for managing interference caused by the first station transmitting the first signal based on knowledge about the first signal and information on the specific processing scheme.

According to the present invention, a network and a terminal can efficiently transmit and receive signals in a wireless communication system.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a diagram illustrating an E-UMTS (Evolved Universal Mobile Telecommunications System) network structure as an example of a wireless communication system.
2 is a conceptual diagram of an evolved universal terrestrial radio access network (E-UTRAN) network structure.
3 is a view for explaining a physical channel used in a 3GPP system and a general signal transmission method using the same.
FIG. 4 is a diagram illustrating an exemplary Full-Duplex Radio (FDR) system.
5 is a view for explaining interference in the FDR system.
6 is a diagram for modeling interference in an FDR communication system.
7 and 8 are views showing a structure of a transmitter and a receiver having multiple antennas in an FDR system, respectively.
Figure 9 illustrates an exemplary system employing a preferred embodiment of the present invention.
10 is a view for explaining an embodiment of the present invention.
11 shows the relationship between the channels when the MS 2 operates as a mobile repeater.
12 shows an example of processing a signal in a repeater.
FIG. 13 shows an example of self interference cancellation.
Figure 14 illustrates an exemplary system employing analog / digital interference control in FDR.
Fig. 15 shows an example of antenna cancellation.
16 shows an example of performing antenna interference control based on the signal bandwidth and the center frequency.
17 is a configuration diagram of a communication device according to the present invention.

The structure, operation and other features of the present invention will be understood by the embodiments of the present invention described in conjunction with the accompanying drawings. The following embodiments are examples in which the technical features of the present invention are applied to a 3GPP (third generation partnership project) system.

Embodiments of the present invention are described herein using an LTE system and an LTE Advanced (LTE-A) system, but these are merely illustrative. Thus, embodiments of the present invention are applicable to any other communication system according to the above definition.

2 is a conceptual diagram of an evolved universal terrestrial radio access network (E-UTRAN) network structure. The E-UTRAN system is an evolved form of the existing UTRAN. The E-UTRAN includes cells (eNBs) interconnected via the X2 Internet. The cell is connected to the terminal via the air interface and is connected to the evolved packet core (EPC) via the S1 interface.

The EPC includes a Mobility Management Entity (MME), a serving gateway (S-GW), and a packet data network-gateway (PDN-GW). The MME mainly has information on the connectivity and the capacity of UEs used for managing mobility of UEs. The S-GW is a gateway having an E-UTRAN as an end point, and the PDN-GW is a gateway having a packet data network (PDN) as an end point.

3 is a view for explaining a physical channel used in a 3GPP system and a general signal transmission method using the same.

The UE performs an initial cell search operation such as synchronizing with the eNB when the UE is turned on or newly enters the cell (S401). To this end, the UE may receive a primary synchronization signal (PSS) and a secondary synchronization channel (SSS) from the eNB, synchronize with the eNB, and obtain information such as a cell ID. The UE can then receive the PBCH from the eNB to obtain in-cell broadcast information. Meanwhile, the UE may receive a downlink reference signal (DL RS) in the initial cell search step to check the downlink channel state.

Upon completion of the initial cell search, the UE can acquire more specific system information by receiving a physical downlink control channel (PDCCH) and a physical downlink control channel (PDSCH) according to information on the PDCCH (S402).

On the other hand, if there is no radio resource for initial connection to the eNB or signal transmission, the UE may perform a random access procedure (RACH) for the eNB (S403 to S406). To this end, the UE may transmit a specific sequence as a preamble on a physical random access channel (PRACH) (S403), and may receive a response message for the preamble on the PDCCH and the corresponding PDSCH (S404 ). In case of a contention-based RACH, a contention resolution procedure can be additionally performed.

The UE having performed the above-described process can perform PDCCH / PDSCH reception (S407) and PUSCH / PUCCH transmission (S408) from the eNB as a general UL / DL signal transmission process. In particular, the UE receives downlink control information (DCI) through the PDCCH. Here, the DCI includes control information such as resource allocation information for the UE, and formats are different according to the purpose of use.

Meanwhile, the control information transmitted by the UE to the eNB through the uplink or received by the UE from the eNB includes a downlink / uplink ACK / NACK signal, a channel quality indicator (CQI), a precoding matrix index a matrix index (PMI), a rank indicator (RI), and the like. In the 3GPP LTE system, the UE may transmit control information such as CQI / PMI / RI through the PUSCH and / or PUCCH.

As described above, according to the present invention, in a full-duplex radio (FDR) communication environment in which transmission and reception are simultaneously performed using the same frequency-time resource, a terminal and a base station, which can be utilized as a mobile relay, An interference cancellation scheme for a base station will be described. Unlike time division duplex (TDD) and frequency division duplex (FDD), which are common Half-duplex schemes, FDR performs simultaneous transmission and reception using resources in the same time-frequency domain, / Downward interference occurs at the same time. In mobile relay, one of the most effective use cases of FDR, the interference characteristics of FDR can reproduce unnecessary interference. Therefore, it is necessary to control interference caused by mobile relay to ensure sufficient communication performance.

In the present invention, the principle of self-interference cancellation of FDR is utilized in handling link-to-link interference caused by a desired signal transmitted from a mobile relay. Thus, it is possible to guarantee stable reception performance at the receiving end of the base station and the neighboring terminal.

FIG. 4 is a diagram illustrating an exemplary Full-Duplex Radio (FDR) system.

Generally, the term "full duplex" refers to a technique of a transmitting terminal that supports transmission of an uplink / downlink by dividing an uplink / downlink into frequency / time without being duplexed. That is, Fig. The terminal 1 and the terminal 2 communicate with each other using the same frequency / time resource, as shown in FIG. 4, so that each terminal must transmit and receive signals transmitted from other base stations or terminals. Therefore, as shown in the curve of FIG. 4, a basic communication environment is created in which the transmission signal of its own can directly induce magnetic interference with the reception antenna.

Considering the multi-cell layout environment as a whole, the new interference or increased interference expected by the introduction of FDR can be summarized as follows.

- Self-user interference

- Multi-user interference

- Inter BS (or eNB) interference

5 is a view for explaining interference in the FDR system.

Self-user interference means that its own transmission signal as shown in FIG. 4 directly causes interference to the receiving antenna. In general, it is important that self-interference is completely removed through removal, because it is received about 60-90 dB stronger than its desired signal.

Second, multi-user interference refers to interference occurring between terminals as shown in FIG. In the conventional communication system, since a half-duplex (e.g., FDD, TDD) that separates the uplink and downlink in frequency or time is implemented, interference does not occur between the uplink and downlink. However, in the full-duplex transmission, since the uplink / downlink share the same frequency / time resources, interference always occurs between the base station transmitting data and neighboring terminals as shown in FIG.

Finally, Inter BS interference refers to the interference that occurs between base stations. This means the same communication situation as multi-user interference, which means that interference always occurs due to uplink / downlink resource sharing between base stations. That is, FDR can increase the frequency efficiency by sharing the same time / frequency resources on the uplink / downlink, but there may be a restriction on improving the frequency efficiency due to the increase of the interference.

Hereinafter, a method for managing such interference will be described.

6 is a diagram for modeling interference in an FDR communication system.

In order to explain the conventional magnetic interference cancellation method in the FDR communication environment, the FDR communication environment shown in FIG. 6 is assumed. Both eNBs and UEs can transmit and receive at the same time-frequency resource at the same time. In order to explain the application of the magnetic interference cancellation technique, a conventional magnetic interference cancellation method is described through a procedure of removing magnetic interference from a signal received from a terminal of a terminal.

It is assumed that both the eNB and the UE in Fig. 6 have multiple antennas.

eNB (base station) Number of transmit antennas: Mtx

eNB (base station) Number of receiving antennas: Mrx

Number of UE (Terminal) transmission antennas: Ntx

Number of UE (Terminal) receiving antennas: Nrx

7 and 8 are views showing a structure of a transmitter and a receiver having multiple antennas in an FDR system, respectively.

In this case, the desired signal (H D ) and the self-interference signal (H I ) of the UE are simultaneously input to the receiving antenna of the real UE.

Finally, if the self-interference cancellation technique through filtering is not applied at the transmitting / receiving end, the total signal received at the UE's receiver is expressed as follows.

Figure 112016501352737-pct00001

Here, the transmitter filtering G tx can be applied in common, or the identity matrix can be applied.

Figure 9 illustrates an exemplary system employing a preferred embodiment of the present invention.

In an embodiment of the present invention, an FDR communication scenario in which a mobile repeater as shown in FIG. 9 is operated is assumed. At this time, the mobile relay may be a base station, a small base station, or a mobile station. In the left part of FIG. 9, the BS transmits the same information to MS 1 and MS 2 at the same time, or transmits broadcast information, and MS 1 transmits uplink information to the BS using the same frequency-time resources at the same time. Here, since the MS 2 is operated as a mobile repeater, it must transmit the received downlink information to the MS 3. Therefore, since the MS 2 needs a processing time to decode information received from the base station, the MS 2 transmits the corresponding information to the MS 3 after a predetermined time delay. The right side of FIG. 9 shows a process in which the MS 2 transmits a signal received in the previous frame / subframe to the MS 3 and simultaneously receives new information from the BS. At this time, the signal transmitted from the mobile repeater MS2 to the MS 3 causes interference to the BS and the neighbor MS1. However, if the information included in the MS2-induced interference signal is broadcast information known to the MS1 and the BS, the corresponding interference signal can be defined differently.

The broadcasting information relayed by the mobile repeater is known information. This is because the base station simultaneously transmits the same information to the mobile terminals as well as the mobile repeater. Since the mobile repeater transmits the received information after the delay time (frame / subframe), the base station and neighboring terminals already know the signal.

However, the base station and neighboring terminals can not accurately predict the signal transmitted by the mobile repeater. This is because the mobile repeater performs processing based on pre-coding, resource allocation information, modulation and coding information in transmitting the target terminal for the purpose, but the base station and the neighboring terminals can not know about it.

Therefore, in an embodiment of the present invention, the above-mentioned example relay station informs the base station or other terminal (s) of the information used for such processing so that the base station or other terminal (s) Thereby performing interference management (interference cancellation). That is, the present invention proposes a method that can utilize the interference generated through the operation of the mobile repeater as a useful signal for the magnetic interference control in the FDR communication.

Basically, since the base station knows all the signals relayed by the mobile repeater, the base station regards it as self-interference and can be removed using the principle of magnetic interference cancellation applied in a general FDR environment. It is possible to utilize the principle of magnetic interference cancellation for the signal relayed by the mobile repeater only when it is broadcast information transmitted to the mobile repeater. To this end, in this embodiment, when a mobile repeater transmits relay information, it proposes to transmit a modulation technique, beamforming, and resource allocation information of the corresponding information to a base station or neighboring terminals.

10 is a view for explaining an embodiment of the present invention.

The MS 2 operating as the mobile repeater of FIG. 10 relays information for the MS MS3 that is outside the base station coverage for information or packets that the BS transmits to the terminals in the cell in common.

Specifically, as shown in FIG. 10, the MS 2 operating as the mobile repeater assumes that the relay information transmitted in the previous subframe is transmitted to the MS 3 (cell-edge MS) after the 'N subframe' delay. For example, information transmitted from the SF (subframe) # 0 is transmitted to the MS 3 in the next subframe SF # 1 (when N = 1). Therefore, the mobile repeater should preferentially detect and decode broadcast information sent from the base station.

At this time, a signal transmitted from the mobile repeater to the MS MS3 in the next frame may interfere with the BS and the neighbor MS1.

11 shows the relationship between the channels when the MS 2 operates as a mobile repeater.

If the mobile repeater relays the same packet to the MS 3 with a delay time of 'N = 1' subframe as shown in FIG. 11, the signal vector r (n) received by the base station BS, the neighboring MS 1, and the mobile repeater MS 2 BS , r 1 , and r 2 can be expressed by the following equations (2) to (4).

Figure 112016501352737-pct00002

Figure 112016501352737-pct00003

Figure 112016501352737-pct00004

Assuming UL / DL channel symmetry, the uplink / downlink channel can be expressed by Equation (5).

Figure 112016501352737-pct00005

Here, F BS , F 1 , and F 2 represent precoding matrices used by the base station (BS), MS 1, and MS 2 for beamforming. For example, if beamforming is not performed, F BS , F 1 , and F 2 become I-matrices. X m represents a UL data signal is transmitted to the base station adjacent to the terminal (MS1), the broadcast information different from X k is irrelevant. X ' k denotes a signal that has undergone channel coding and decoding (MCS) after decoding the base station information X k in order to transmit the mobile relay MS 2 to the cell edge MS 3.

Hereinafter, it is assumed that the subframe delay N = 1 of the mobile repeater will be described.

When detecting the desired signal H B1 F 1 X m sent from the MS 1 as in Equation (2), the base station must know the information of H B 2 F 2 X ' k of the interference signal caused by the mobile repeater, After the reconstruction, interference cancellation can be performed. The desired signal transmitted by the base station of the neighbor MS1 is H 1 B F BS X k +1 . Where H 12 F 2 X ' k is the interference signal induced by the signal transmitted by the mobile repeater.

In equations (2) and (3), it can be seen that the interference component caused by the mobile repeater MS2 is the information packet #K obtained in the previous subframe SF # 0 by the base station and the neighboring MS MS1. Therefore, if the neighboring BS and the MS can know the modulation scheme, beamforming information, and resource allocation information used in the signal transmission transmitted from the mobile repeater, the signal transmitted from the mobile repeater can be completely restored at each receiving station.

12 shows an example of processing a signal in a repeater.

As shown in FIG. 12, a relay station receives information 'packet # k' and performs processing such as channel coding, modulation, precoding, resource mapping, OFDM signal generation, Signal can be transmitted.

As shown in FIG. 12, the information 'packet # k' is information that the base station, the neighboring terminal, and the mobile repeater have. Therefore, the neighboring mobile station and the base station can once again confirm that the mobile repeater can completely recover the corresponding signal at each stage when knowing the modulation / beamforming / resource allocation method of broadcast information.

Specifically, the modulation and coding scheme (MCS) is such that Packet # K is transformed into X ' k , beamforming (generally precoding) is F 2 and resource allocation is of a relay signal Time-frequency domain allocation position.

Therefore, when the mobile repeater broadcasts the modulation / beamforming / resource allocation method used for relay information transmission to neighboring terminals and the base station, interference cancellation as described above can be implemented. How to create broadcasting information is as follows.

- Modulation and coding scheme (MCS) information

The code-rate and QAM level used by the mobile repeater in modulating the relay information can be predetermined. By pre-setting this set, you can transfer information in a simple bit-map format. For example, if a total of 16 code-rate and QAM levels are supported as shown in Table 1, the total 4-bit information is broadcasted.

Figure 112016501352737-pct00006

- About Beamforming

Beamforming generally refers to precoding, which should produce an optimal beam direction for the terminal to be relayed based on the estimated channel. If beamforming is not applied, the beamforming matrix used by the mobile repeater becomes F 2 ? I Nt . That is, I-matrix. The precoding matrix may also be defined in advance. For example, if a total of 4 precoding matrices are defined as shown in Table 2, the total 2-bit information is broadcasted.

Figure 112016501352737-pct00007

- Resource allocation information

The mobile repeater can acquire the resource allocation information by using the fixed resources when relaying the broadcast information to the neighboring terminal. Or through semi-static configuration through periodic signaling.

- channel estimation

It is assumed that the channel between each link can be estimated through a commonly used pilot setting.

In the above-described embodiment, it has been proposed that the mobile repeater directly provides information to the BS and the neighboring MS (s) for processing signals for transmission to the MS it is servicing. Meanwhile, in another embodiment of the present invention, it is proposed that the mobile station feeds back the modulation scheme, precoding, and resource allocation information for relayed information to the base station, and the base station broadcasts the same information to the terminals in the cell. In this manner, the base station / neighboring terminal can also perform interference management by acquiring processing information used by the repeater.

In another embodiment, the mobile repeater can simultaneously broadcast the modulation scheme, precoding, and resource allocation information for the relayed information to the base station and neighboring terminals.

In another embodiment of the present invention, it is proposed that a base transceiver station and a neighboring mobile station regard a mobile repeater transmission signal that is already known as self interference. The base station and neighboring mobile stations can reconstruct each mobile station based on the information received from the mobile station. Therefore, it is possible to apply the same principle as assumed in the case of FDR self-interference cancellation. However, the same interference can be eliminated even when the mobile station relays the information to be transmitted only to the cell boundary mobile stations, as well as when transmitting the broadcast information to all the mobile stations.

- channel estimation

It is assumed that the channel H B 2 between the mobile repeater and the base station is already known through the channel estimation. That is, the base station / terminal can perform channel estimation when the mobile repeater transmits pilot for uplink transmission.

- Precoding information

The precoding information of H B 2 F 2 X ' k means F 2. If it is assumed that the cell boundary MS 3 is a static terminal, it can be known through periodic broadcasting of the mobile repeater.

Transmission signal (modulation scheme): H B 2 F 2 X ' k Lt ; RTI ID = 0.0 & gt; X'k. ≪ / RTI > That is, when channel coding and QAM modulation are performed, it is assumed that the combination is selected semi-static. Through this, it can be seen the actual travel modulation end signal X 'k is generated by the repeater.

Since the base station has finally obtained all the information about the interference caused by the mobile repeater, it can be subtracted from the received signal after reconstruction of the signal. That is, in the case of Equation (2), when the corresponding reconstruction signal is subtracted, it can be expressed as follows.

Figure 112016501352737-pct00008

Here, e is a component that reflects a channel estimation error that may occur basically and a minute error of the signal process, even though the signal generation information of the mobile repeater is completely known. However, it can be assumed that the value is considerably low.

From this simple signal subtraction, it is possible to apply both analogue elimination and digital elimination techniques that can be used to remove magnetic interference in FDR.

Hereinafter, an interference cancellation method for performing such a method will be described.

FIG. 13 shows an example of self interference cancellation.

As mentioned above, self-interference generally refers to the interference that occurs when the transmission signal of its own is received directly at the receiving antenna. In this case, the magnitude of the interference may be about 60-90 dB larger than the actual received signal. As shown in FIG. 13, there are three methods for removing the self-interferences. The maximum removal range according to each technique is as follows.

Antenna removal: 20-30 dB

Analog elimination: Max, 45dB

Digital Elimination: 20-25dB

The application position of each technique is shown in FIG. In other words, it is digital elimination that the signals processed by the base band are applied before the DAC or after the ADC. In digital elimination, various interference cancellation techniques such as beamforming can be applied to perform self interference cancellation (SIC), and the range is about 20-25 dB.

Next is the analog cancellation, which goes through the DAC or is processed by the RF signal before going through the ADC.

Figure 14 illustrates an exemplary system employing analog / digital interference control in FDR.

As shown in FIG. 14, the analog cancellation means that the analog cancellation signal is directly generated through the digital estimation of the self-interference in the second transmission chain, and then the signals are combined in the RX stage. This is done through SIC. FIG. 14 simultaneously shows a transmission / reception terminal structure implementing such analog interference cancellation and digital interference cancellation. In other words, in the analog interference cancellation technique, the signal itself of the transmitter is inverted and added to the signal of the receiver so that the directly received signal disappears.

Fig. 15 shows an example of antenna cancellation.

This is because the transceiver composed of two Tx antennas and one Rx antenna has a 180-degree inversion phase when the signals transmitted from the two transmit antennas enter the receive antenna, so that the phase of the signal transmitted from the two transmit antennas is 180 degrees . Through this, the summation signal received at the centrally located Rx antenna becomes null or zero. FIG. 15 shows a simple implementation of this antenna cancellation technique. Here, the distance between the two Tx antennas and the Rx antenna differs by exactly ? / 2. Therefore, the phase difference is exactly 180 degrees.

In general, the antenna removal technique has a low complexity and the simplest implementation is simple. However, as mentioned above, the maximum removal performance of the antenna cancellation technique is generally known to be about 20-30 dB. However, for FDR systems, SIC performance of about 70dB is required, and this technique can generally be achieved by a combination of the three techniques mentioned above.

However, there is a specific communication environment in which the performance of the antenna cancellation technique can be maximized, and the present invention is preferably applied to such a communication environment.

16 shows an example of performing antenna interference control based on the signal bandwidth and the center frequency.

Generally, the smaller the system bandwidth, the higher the performance of the antenna IC as the center frequency becomes higher. 16 is a graph showing the performance of such an antenna IC. From this, it can be seen that as the center frequency increases, the graph drops to the left as the system graph becomes lower and the system bandwidth becomes smaller.

Therefore, this phenomenon can lead to one insight. When the high frequency narrowband is allocated to the FDR communication area, sufficient SIC performance can be ensured by removing only the antenna, so that the performance of the FDR can be guaranteed and the implementation complexity can be reduced. Generally, the high-frequency transmission band is intended for broadband communication using a wide frequency band. Therefore, when the FDR zone is used for a part of the high-frequency transmission band, an advantageous environment for self-interference cancellation through the antenna IC is created, Can be derived.

Hereinafter, zero-forcing filtering and MMSE filtering will be described as methods for removing magnetic interference.

Zero-forcing filtering is the simplest method for improving performance through null space projection at the transmitting and receiving end. That is, the Eigen value of the interference channel H I is projected to the zero-rank interference signal. Through this, the transmitted signal is emitted from the transmitter, but has no effect on the receiver. Since this ZF filtering can be implemented simply, it can be applied to both the transmitter and the receiver. Tx filtering and Rx filtering implemented in the transmitting and receiving end can be easily implemented by Equations 7 and 8 using the following pseudo-inverse matrix.

Figure 112016501352737-pct00009

Figure 112016501352737-pct00010

(·) + Represents a pseudo-inverse matrix.

The received signal to which the filtering is applied is finally changed as shown in Equation 9 below. Here, if complete self-interference cancellation is achieved,

Figure 112016501352737-pct00011
, Leaving only the desired signal and noise.

Figure 112016501352737-pct00012

Meanwhile, MMSE filtering is a method applied at the receiving end. That is, it is a method of minimizing the MSE in the received signal. Therefore, Tx filtering can apply ZF Tx filtering as it is. In this case, it is expected that the total interference cancellation performance is improved. MMSE Rx filtering alone is sufficient to eliminate self interference, and the transmitter adopts the same G tx as ZF and applies MMSE filtering only to G rx as shown in Equations (10) and (11) below.

Figure 112016501352737-pct00013

Figure 112016501352737-pct00014

The received signal to which MMSE Rx filtering is applied is finally changed as shown in Equation 12 below. That is, ZF Rx filtering is applied to Equation 9, and finally G rx is realized as Equation 11.

Figure 112016501352737-pct00015

As described above, in the present invention, in the communication between a terminal and a base station in a full-duplex radio (FDR) communication environment in which transmission and reception are simultaneously performed using the same frequency-time resource, interference cancellation The method was described. Unlike time division duplex (TDD) and frequency division duplex (FDD), which are common Half-duplex schemes, FDR performs simultaneous transmission and reception using resources in the same time-frequency domain, / Downward interference occurs at the same time. Mobile repeaters, one of the most useful use cases of FDR, can reproduce unnecessary interference due to the interference characteristics of FDR. Therefore, the communication performance is sufficiently ensured by controlling the interference caused by the mobile repeater. In the present invention, in order to process link-to-link interference caused by a desired signal transmitted from a mobile repeater, a principle of self-interference cancellation of FDR is utilized. Thus, it is possible to guarantee stable reception performance at the receiving end of the base station and the neighboring terminal.

Hereinafter, a configuration of a device for performing such a method will be described.

17 is a configuration diagram of a communication device according to the present invention.

The apparatus shown in FIG. 17 may be a user terminal and / or a base station configured to perform the above-described mechanism, but any apparatus for performing the same operation is possible.

As shown in FIG. 17, the device may include a DSP / microprocessor 110 and an RF module (transceiver) 135. The DSP / microprocessor 110 is coupled to and controls the transceiver 135. Depending on the configuration and designer's intent, the device may include a power management module 105, a battery 155, a display 115, a keypad 120, a SIM card 125, a memory device 130, a speaker 145, And may further include an input device 155.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Accordingly, it is intended that the scope of the invention be construed as including all such modifications and alterations within the scope and spirit of the appended claims.

Although the above-described method has been described with reference to an example applied to the 3GPP LTE system, the present invention is applicable to various wireless communication systems in addition to the 3GPP LTE system.

Claims (16)

  1. A method for receiving a signal from a base station (BS) directly served by a BS in a mobile communication system,
    The first station receives a first signal from the base station during a first time interval,
    A second station, which is a repeater, transmits information about a particular processing scheme of the second station that the second station applies to transmit the first signal to a third station serviced by the second station, From the second station,
    The first station receives a second signal from the base station during a second time interval during which the second station transmits a first signal processed according to a particular processing scheme of the second station to the third station,
    Wherein the second time interval is a time interval different from the first time interval,
    The first station receives the second signal from the base station,
    Wherein the first station is configured to receive interference caused by the first signal transmission from the second station based on knowledge of the first signal and information on the particular processing scheme among signals received during the second time interval And acquiring the second signal transmitted from the base station.
  2. The method according to claim 1,
    Wherein the specific processing scheme comprises at least one of a modulation and coding scheme, a precoding scheme and a resource allocation scheme.
  3. The method according to claim 1,
    Wherein the first signal is a broadcast signal broadcast by the base station to a plurality of stations including the second station.
  4. The method according to claim 1,
    Wherein information on the particular processing scheme is received and obtained from the second station on information about the particular processing scheme.
  5. The method according to claim 1,
    And information on the specific processing scheme is obtained by estimating and obtaining information on the specific processing scheme in the first station.
  6. The method according to claim 1,
    And information on the particular processing scheme is received and obtained from the base station for information about the particular processing scheme.
  7. delete
  8. A method for relaying a signal in a first station, which is a repeater in a mobile communication system,
    Receiving, during a first time interval, a signal to be transmitted from a base station to a second station serviced by the first station,
    Processing the received signal according to a specific method,
    Wherein the first station transmits the processed signal to the second station during a second time interval in which at least one of the base station and a third station directly serviced by the base station receives another signal,
    Wherein the second time interval is a time interval different from the first time interval,
    And transmits information about the specific scheme to one or more of the base station and the third station.
  9. 9. The method of claim 8,
    Wherein the information about the particular scheme is used by the at least one of the base station and the third station to manage interference that occurs as a result of transmitting the processed signal to the second station.
  10. 10. The method of claim 9,
    Wherein at least one of the base station and the third station knows the received signal,
    Wherein at least one of the base station and the third station manages the interference based on information about the specific scheme and knowledge of the received signal.
  11. 9. The method of claim 8,
    Wherein the mobile communication system uses an FDR (Full-Duplex Radio) communication method.
  12. delete
  13. A method for a base station to receive a signal in a mobile communication system,
    Transmitting a first signal to a first station that is a repeater during a first time interval,
    Wherein the first station receives from the first station information on a particular processing scheme that the first station applies to transmit the first signal to a second station serviced by the first station,
    The base station receives a second signal from a third station during a second time period during which the first station transmits the first signal to the second station,
    Wherein the second time interval is a time interval different from the first time interval,
    The base station receives the second signal from the third station,
    The base station removes the interference caused by the first station transmitting the first signal based on the information on the specific processing scheme and the knowledge of the first signal among the signals received during the second time period And acquiring the second signal transmitted from the third station.
  14. An apparatus for operating in a mobile communication system as a first station and relaying signals,
    A transceiver for receiving a signal from a base station; And
    And a processor coupled to the transceiver to control operation of the first station,
    The processor controls the transceiver to:
    Receiving, during a first time interval, a signal to be transmitted from the base station to a second station serviced by the first station,
    Processing the received signal according to a specific method,
    Wherein the first station transmits the processed signal to the second station during a second time interval in which at least one of the base station and a third station directly serviced by the base station receives another signal,
    Wherein the second time interval is a time interval different from the first time interval,
    And transmits information about the specific scheme to at least one of the base station and the third station.
  15. 1. An apparatus for receiving a signal from a base station in a mobile communication system and operating as a first station directly served by the base station,
    A transceiver for transmitting and receiving signals with the base station and a second station as a repeater; And
    And a processor coupled to the transceiver to control operation of the first station,
    The processor controls the transceiver to:
    Receiving a first signal from the base station during a first time interval,
    From the second station, information about a particular processing scheme of the second station applied by the second station to transmit the first signal to a third station serviced by the second station, and,
    The first station receives a second signal from the base station during a second time interval during which the second station transmits a first signal processed according to a particular processing scheme of the second station to the third station,
    Wherein the second time interval is a time interval different from the first time interval,
    The processor receives the second signal from the base station,
    Wherein the processor removes interference caused by the first signal transmission from the second station based on knowledge of the first signal and information on the particular processing scheme among signals received during the second time interval And acquiring the second signal transmitted from the base station.
  16. An apparatus operating as a base station in a mobile communication system,
    A transceiver for transmitting and receiving signals to and from a first station and a second station that are repeaters; And
    And a processor coupled to the transceiver to control operation of the base station,
    The processor controls the transceiver to:
    Transmitting a first signal to the first station during a first time interval,
    From the first station, information about a particular processing scheme applied by the first station to the first station to transmit the first signal to a second station serviced by the first station,
    The base station receives a second signal from a third station during a second time period during which the first station transmits the first signal to the second station,
    Wherein the second time interval is a time interval different from the first time interval,
    And the processor receiving the second signal from the third station,
    The processor eliminates the interference caused by the first station transmitting the first signal based on the information about the specific processing scheme and the knowledge of the first signal among the signals received during the second time period And acquiring the second signal transmitted from the third station.
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